# How can a t-statistic be used to determine statistical significance?

For eg; the statistic: t = ($\overline{x}$ - $\mu$ )/sqrt (n - 1), where $\mu$ is the population mean of a N($\mu$ ,$\sigma$ )population with $\sigma$ unknown, follows student's t with n- 1, degrees of freedom and it can be used to test the significance of the hypothesis ${H}_{0}$ : $\mu$ = (mu)_0